Generators are your only long-term (12+ hour) solution. I know you can purchase a generator that can run a full-size fridge, a full-size freezer, and most of the lights/TVs in my house for like $5-600...if the ONLY thing you're worried about is your tank, you could probably find something (or put something together) that's a lot cheaper...just make sure you keep the gas tank full when you're running it...most generators I've worked with would run about 12 hours on a tank of fuel.